Don't remember an unfair SIM in almost 30 years, a couple of less enjoyable occasions would have been more pleasant with better preparation on my part. The legal necessities require so many "must-have" items during training that there is actually very little leeway for the instructor to add or deduct without risking to make the check invalid. Fail too little and a required failure is missing, fail too much and a subsequent approach or go-around cannot be flown the way it's required to meet the criteria.
IMHO checks may and should be harder than what may be expected in real life. Airplane systems don't know they're not supposed to fail in pairs, and I prefer walking off a sim sweaty saying "if I could handle this, I can handle most stuff that's actually likely to happen to me in real life" than sticking to a "no multiple failures" protocol just to have more than one piece of **** hit the fan out in the clouds. Even more so for training events. Fresh from training everyone can hand-fly on instruments, even partial panel. Why not use checks and trainings to keep that skill rather than moaning that "those youngsters can't fly without a flight director" when we never ask them to hone/keep that skill. So give me some electrics or hydraulics fault on top of my V1 cut to keep me busy, even if I swear.